The shopping mall giant announced late Thursday that Art Coppola would step down as CEO of the Santa Monica-based real estate investment trust at the end of the year after a quarter century at its helm. The 65-year-old became CEO in 1993 and was a founding member of the company’s predecessor, Macerich Group, in 1976.

The announcement comes at a tough time for Macerich, as the company navigates a trend away from brick-and-mortar retail towards e-commerce. Shares in the REIT are down 12.4 percent this year, giving the company a value of $8.1 billion, according to Bloomberg. Shares fell 2.9 percent earlier Thursday but recovered to close 0.9 percent for the day at $57.55.

Coppola will also step down from his role as chairman of the company’s board. It’s Lead Independent Director since August 2017, Steven Hash, has been appointed Independent Chairman. The board has started a process to determine a successor to Coppola.

While it’s unclear what prompted Coppola to step down, the shakeup comes amid board-level activity from activist investors. Starboard Value nominated a majority slate of directors to the company’s board, sources told Bloomberg earlier this month. Third Point also disclosed a stake in the company in November.

Coppola oversaw the newly formed Macerich Company’s initial public offering in 1994 within his first year as CEO of the company. During his tenure the company’s market cap grew from around $600 million to $16 billion, according to a press release. The company currently owns 48 retail properties nationwide.

Macerich rejected a $16.8 billion merger offer from rival Simon Property Group in April 2015, a month after its stock hit a post-recession high of around $94, saying the bid undervalued the company and its growth prospects, according to the Wall Street Journal. Its stock has steadily declined from a recent high of just under $90 reached in August 2016.

Earlier this year the company surprised many in Los Angeles when it announced a partnership with Hudson Pacific Properties to convert its struggling Westside Pavilion mall into a creative office property. The partnership sees Macerich selling HPP a 75 percent stake in the property.